The present invention relates to backflow preventing devices for installation in a pressurized fluid flow system for preventing reverse flow of fluid through the system and, more particularly, relates to such devices of the type commonly referred to as hose connection vacuum breakers.
Over recent years, there has been significantly mounting ecological concern for the prevention of pollution or other contamination of potable water supplies. In pressurized flow system for drinking water, contamination of the potable water supply may occur by the undesired reverse flow into the system of previously discharged water which has become contaminated. This so-called "backflow" or "back-siphonage" may occur, for instance in the ordinary use of a conmon garden hose when discharged water remaining within the hose is drawn back into the potable water supply system by the creation of a vacuum in the supply line to which the hose is connected or, alternatively, when the terminal end of the hose is held at a higher elevation than the hose connection to the supply line from the potable water supply system simultaneously with a loss in the water supply pressure creating a greater fluid pressure downstream within the hose. Possible contamination of the potable water supply is particularly dangerous if the garden hose has been utilized for spraying toxic insecticides, fertilizers or like chemicals.
To prevent the above-described risk of water contamination, backflow preventing devices of a type commonly referred to as hose connection vacuum breakers have been developed for attachment to the discharge nozzle of conventional water faucets such as commonly provided on an exterior wall of a residential home for garden hose connection. Essentially, such backflow preventing devices provide a tubular body assembly with a threaded female-type inlet connection for mounting on the conventional threaded male-type outlet nozzle utilized on most conventional faucets and a threaded male-type outlet connection for attachment of a garden hose or similar flow conduit. A check valve assembly is provided in the passageway of the backflow preventing device between its inlet and outlet ends for permitting ordinary pressurized water flow from the inlet end to the outlet end while preventing reverse flow. some form of relief port in the body of the device permits any reversely flowing water to drain to the exterior of the body. Substantially all public water supply systems now require that appropriate backflow preventing devices such as these vacuum breakers be utilized in connecton with faucets and other discharge control valves connected in the system.
All known conventional hose connection vacuum breakers employ a multipiece tubular body which is relatively expensive to fabricate and assemble, as well as requiring proper sealing between the assembled pieces. Furthermore, conventional vacuum breaker devices provide a transverse wall separating the inlet and outlet end of the assembled body with multiple holes formed through the wall to provide inlet-to-outlet flow and the check valve operating against the separating wall to prevent reverse flow. Disadvantageously, the separating wall constricts the flow passageway through the vacuum breaker device and the holes formed in the wall are subject to clogging.
In contrast, the present invention provides an improved backflow preventing device, preferable of the hose connection vacuum breaker type, which is of a simplified one-piece body construction which eliminates the use of a separating wall to provide a more unobstructed flow passageway in the open operating condition of the device.